It has long been known that implantable medical electrical leads may be positioned transvenously within one or more chambers of the heart or the associated vascular system to provide electrical stimulation to cardiac tissue. Often, such a lead includes multiple electrodes. For example, a lead may include a pair of pace/sense electrodes. This electrode pair may be used to deliver low-voltage stimulation such as pacing pulses to the tissue. Often, the electrode pair will include a tip electrode that is used as the cathode to supply such pacing pulses. In the case of electrodes positioned within the cardiac vasculature, this is not necessarily the case, however. That is, when electrodes are positioned within a vein, the most distally-positioned electrode is not necessarily the best electrode choice for use as the cathode. In this type of situation, threshold testing may be performed to determine which electrode of an electrode pair will provide better capture of the heart, and is therefore more suitable for use as the cathode.
As another example, some leads include one or more pace/sense electrodes to provide pacing and sensing capabilities, and at least one additional high-voltage electrode to provide high-voltage therapy, including cardioversion/defibrillation shocks. In some instances, it is advantageous to electrically couple the high-voltage electrode with at least one of the pace/sense electrodes prior to high-voltage therapy delivery, since this increases the amount of tissue affected by the therapy. In other words, it increases the “shadow area” of the high-voltage electrode. Preferably, one or more pace/sense electrodes being uses as an anode during pacing therapy is selected for electrically coupling to the high-voltage electrode.
In either of the above-described examples, it is necessary to selectively couple an electrode to circuitry within an implantable pulse generator or another signal generator. This electrical coupling is generally performed after threshold testing or another type of electrical signal testing is performed. However, current lead systems do not provide a mechanism for readily these types of selective connections. Therefore, what is needed is an improved connection system for a multi-polar lead that will solve at least some of the foregoing problems.